/*
 * ------------------------------------------------------------------------
 *  Copyright by KNIME AG, Zurich, Switzerland
 *  Website: http://www.knime.com; Email: contact@knime.com
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License, Version 3, as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses>.
 *
 *  Additional permission under GNU GPL version 3 section 7:
 *
 *  KNIME interoperates with ECLIPSE solely via ECLIPSE's plug-in APIs.
 *  Hence, KNIME and ECLIPSE are both independent programs and are not
 *  derived from each other. Should, however, the interpretation of the
 *  GNU GPL Version 3 ("License") under any applicable laws result in
 *  KNIME and ECLIPSE being a combined program, KNIME AG herewith grants
 *  you the additional permission to use and propagate KNIME together with
 *  ECLIPSE with only the license terms in place for ECLIPSE applying to
 *  ECLIPSE and the GNU GPL Version 3 applying for KNIME, provided the
 *  license terms of ECLIPSE themselves allow for the respective use and
 *  propagation of ECLIPSE together with KNIME.
 *
 *  Additional permission relating to nodes for KNIME that extend the Node
 *  Extension (and in particular that are based on subclasses of NodeModel,
 *  NodeDialog, and NodeView) and that only interoperate with KNIME through
 *  standard APIs ("Nodes"):
 *  Nodes are deemed to be separate and independent programs and to not be
 *  covered works.  Notwithstanding anything to the contrary in the
 *  License, the License does not apply to Nodes, you are not required to
 *  license Nodes under the License, and you are granted a license to
 *  prepare and propagate Nodes, in each case even if such Nodes are
 *  propagated with or for interoperation with KNIME.  The owner of a Node
 *  may freely choose the license terms applicable to such Node, including
 *  when such Node is propagated with or for interoperation with KNIME.
 * ------------------------------------------------------------------------
 */

package org.knime.python.typeextension.builtin.datetime2;

import java.io.IOException;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;

import org.knime.core.data.DataCell;
import org.knime.core.data.DataType;
import org.knime.core.data.filestore.FileStoreFactory;
import org.knime.core.data.time.localdatetime.LocalDateTimeCellFactory;
import org.knime.core.data.time.zoneddatetime.ZonedDateTimeCellFactory;
import org.knime.core.node.NodeLogger;
import org.knime.python.typeextension.Deserializer;
import org.knime.python.typeextension.DeserializerFactory;

/**
 * Is used to deserialize python datetime objects to either LocalDateTime
 * objects if no timezoneinfo is given or ZonedDateTime objects if said info is
 * given.
 * 
 * @author Clemens von Schwerin, KNIME.com, Konstanz, Germany
 */

public class DateTime2DeserializerFactory extends DeserializerFactory {

    public DateTime2DeserializerFactory() {
        // Set the type of the resulting column to the conjunction of the
        // LocalDateTimeType and ZonedDateTimeType. (non-native)
        // While the table is created the types included in the resulting
        // columns are tracked and the column type is replaced with
        // the most common super type of all included cells after all cells have
        // been inserted. This means that if only cells of a
        // single data type are present the type will be native.
        super(DataType.getCommonSuperType(LocalDateTimeCellFactory.TYPE, ZonedDateTimeCellFactory.TYPE));
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Deserializer createDeserializer() {
        return new DateTimeDeserializer();
    }

    private class DateTimeDeserializer implements Deserializer {

        ArrayList<ZoneId> tzWithChangedOffset = new ArrayList<ZoneId>();

        /**
         * {@inheritDoc}
         */
        @Override
        public DataCell deserialize(byte[] bytes, FileStoreFactory fileStoreFactory) throws IOException {
            // Deserialize to LocalDateTime or ZonedDateTime based on incoming
            // date string
            String string = new String(bytes, "UTF-8");
            if (string.length() <= 23) {
                DateTimeFormatter formatter = DateTimeFormatter.ofPattern(LocalDateTimeSerializerFactory.FORMAT);
                return LocalDateTimeCellFactory.create(string, formatter);
            } else {
                DateTimeFormatter formatter = DateTimeFormatter.ofPattern(ZonedDateTimeSerializerFactory.FORMAT);
                ZonedDateTime dt = ZonedDateTime.parse(string, formatter);
                //For a zoned datetime coming from python it is possible that the transferred timezone name and 
                //timezone offset do not comply with java defaults (e.g. timezone name = 'Europe\Berlin', offset=5 are
                //received while in Java timezone name 'Europe\Berlin' has an associated offset=2). ZonedDateTime.parse
                //overwrites incorrect offsets without a warning. Therefore we check manually if the received timezone
                //offset of the incoming timestampstring (located between position 23 and 29) equals the offset of the 
                //created ZonedDateTime object. If not a warning is issued so that the user may further look into it.
                if (!tzWithChangedOffset.contains(dt.getZone())
                        && !dt.getOffset().equals(ZoneOffset.of(string.substring(23, 29)))) {
                    // warn
                    NodeLogger.getLogger(DateTimeDeserializer.class)
                            .warn("Offset " + string.substring(23, 29)
                                    + " was changed automatically to the stored offset for timezone " + dt.getZone()
                                    + ". Multiple entries may be affected!");
                    tzWithChangedOffset.add(dt.getZone());
                }
                return ZonedDateTimeCellFactory.create(string, formatter);
            }
        }

    }

}
